What is "The Nations" chapter 15

Now that he's six, Granma pushes him to keep learning dictionary words, though he finds a letter B page has been torn out. Pine Billy comes to visit more often, now that the watermelons have ripened. One time he tells them that he thinks the world is coming to an end. He's heard that out in Oklahoma, the wind was blowing away the ground. Granpa has already received letters from relatives in Oklahoma, formerly part of the Nations. They wrote of how white men had plowed land that shouldn't be plowed, and of how the wind was blowing it all away. Pine Billy has decided he wants to be saved. Since the world is coming to an end, Pine Billy plays sad songs on his fiddle.